1. Field of the Invention
This invention relates to circuits for terminating operation of a motor when a defective condition, such as excessive winding temperature or loss of lubricating fluid pressure, is sensed. Such circuits are often utilized in refrigeration or air conditioning systems.
2. Description of the Prior Art
The prior art, as exemplified in U.S. Pat. Nos. 2,945,133; 3,014,159; 3,241,001; 3,290,576; 3,329,868; 3,312,081; 3,377,816; 3,404,313; 3,416,060; 3,457,460; 3,660,718; and 3,673,811, contains a number of prior art motor protection circuits including circuits which both sense winding overheat conditions and loss of lubricant fluid pressure to terminate operation of a motor. The prior art circuits generally have many deficiencies such as being unreliable, too expensive, capable of being readily rendered ineffective by taping down a reset switch, and the like.